全文获取类型
收费全文 | 26137篇 |
免费 | 2283篇 |
国内免费 | 1044篇 |
专业分类
电工技术 | 1357篇 |
综合类 | 1453篇 |
化学工业 | 4364篇 |
金属工艺 | 1032篇 |
机械仪表 | 1355篇 |
建筑科学 | 1638篇 |
矿业工程 | 460篇 |
能源动力 | 992篇 |
轻工业 | 2074篇 |
水利工程 | 443篇 |
石油天然气 | 627篇 |
武器工业 | 124篇 |
无线电 | 3928篇 |
一般工业技术 | 3475篇 |
冶金工业 | 2165篇 |
原子能技术 | 273篇 |
自动化技术 | 3704篇 |
出版年
2024年 | 59篇 |
2023年 | 265篇 |
2022年 | 506篇 |
2021年 | 746篇 |
2020年 | 526篇 |
2019年 | 582篇 |
2018年 | 658篇 |
2017年 | 616篇 |
2016年 | 699篇 |
2015年 | 870篇 |
2014年 | 1100篇 |
2013年 | 1607篇 |
2012年 | 1583篇 |
2011年 | 1640篇 |
2010年 | 1468篇 |
2009年 | 1473篇 |
2008年 | 1517篇 |
2007年 | 1406篇 |
2006年 | 1356篇 |
2005年 | 1115篇 |
2004年 | 991篇 |
2003年 | 1111篇 |
2002年 | 1313篇 |
2001年 | 1121篇 |
2000年 | 721篇 |
1999年 | 622篇 |
1998年 | 778篇 |
1997年 | 550篇 |
1996年 | 418篇 |
1995年 | 359篇 |
1994年 | 216篇 |
1993年 | 221篇 |
1992年 | 146篇 |
1991年 | 124篇 |
1990年 | 93篇 |
1989年 | 98篇 |
1988年 | 84篇 |
1987年 | 66篇 |
1986年 | 59篇 |
1985年 | 88篇 |
1984年 | 45篇 |
1983年 | 39篇 |
1982年 | 67篇 |
1981年 | 52篇 |
1980年 | 38篇 |
1979年 | 30篇 |
1978年 | 24篇 |
1977年 | 35篇 |
1976年 | 58篇 |
1973年 | 23篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
文章通过对上海“新浦江城”首期项目的介绍,分析了意大利设计在该项目应用中的独特之处,同时指出了存在的一些问题。指出国外设计应结合中国国情,符合社会发展的需要。 相似文献
102.
Dual-Mode Microstrip Open-Loop Resonators and Filters 总被引:1,自引:0,他引:1
A miniature dual-mode microstrip open-loop resonator is proposed. Distinct characteristics of this new type of dual-mode resonator are investigated using full-wave electromagnetic simulations. It is shown that the two operating modes, i.e., the even and odd modes, within a single dual-mode resonator of this type do not couple. It is also found that there is a finite-frequency transmission zero inherently associated with the even mode. Two two-pole filters using this type of dual-mode resonator are demonstrated with opposite asymmetric responses, which result from different locations of the transmission zero. Higher order filters of this type are also investigated. Both simulated and measured results are presented. 相似文献
103.
企业网络信息管理系统的总体设计 总被引:1,自引:0,他引:1
介绍了企业网络信息管理系统总体设计方案,提出了软、硬件的设计方案和实现方法。该系统可以实时掌握控制各职能部门的运营状况,有效地调配企业资源,提高企业的市场竞争能力。 相似文献
104.
依据红外反射式光电探纬的组成和工作原理,对有梭织机光电探纬系统进行了改进。将反光装置(膜)固定在梭芯上,减少了反光装置的数量,无需改动梭子和纬管,系统探纬准确,减少了换梭时纡脚回丝。 相似文献
105.
106.
Yan T Wong Norbert Dommel Philip Preston Luke E Hallum Torsten Lehmann Nigel H Lovell Gregg J Suaning 《IEEE transactions on neural systems and rehabilitation engineering》2007,15(3):425-434
A neurostimulator application-specific integrated circuit (ASIC) with scalable circuitry that can stimulate 14 channels, has been developed for an epi-retinal vision prosthesis. This ASIC was designed to allow seven identical units to be connected to control up to 98 channels, with the ability to stimulate 14 electrodes simultaneously. The neurostimulator forms part of a vision prosthesis, designed to restore vision to patients who have lost their sight due to retinal diseases such as retinitis pigmentosa and macular degeneration. For charge balance, the neurostimulator was designed to stimulate with current sources and sinks operating together, and with the ability to drive a hexagonal mosaic of electrodes to reduce the electrical crosstalk that occurs when multiple bipolar stimulation sites are active simultaneously. A hexagonal mosaic of electrodes surrounds each stimulation site and has been shown to effectively isolate each site, increasing the ability to inject localized independent charge into multiple regions simultaneously. 相似文献
107.
108.
Microwave plasma synthesis of TiN and ZrN nanopowders 总被引:2,自引:0,他引:2
This work demonstrates that TiN and ZrN nanopowders can be prepared by microwave plasma synthesis method. The effects of flow rate of plasma forming gas, flow rate of carrier gas and feeding rate of precursor raw material to the average particle size were studied. The TiN and ZrN nanopowders were characterized by means of transmission electron microscopy (TEM) and X-ray diffraction (XRD). 相似文献
109.
In recent years, the Asia-Pacific region has experienced several financial setbacks, including speculative attacks in 1998 and the SARS outbreak in 2003. Financial stresses of this nature are unanticipated, and not all of the dangers can be predicted by the examination of market information and macroeconomic indicators. The Early Warning System (EWS) that has been adopted by the International Monetary Fund may not be able to predict future financial crises for all possible scenarios, because shocks come in many different forms. To supplement the EWS, this paper proposes a data mining framework to measure the resilience of an economy. The resilience framework does not predict a crisis, but rather assesses the current state of health of an economy and its ability to withstand a financial shock should one occur. The framework is based on a feedback system consisting of two stages. The first stage assigns a resilience score to each economy based on a fuzzy logic scoring scheme that is built on the ambiguous reasoning of experts. The second stage uses the classification tree approach to estimate thresholds for each economic indicator, and examines the quality of the fuzzy score. The result from the second stage is then passed back to the first stage as feedback. The final result is obtained when the feedback system reaches its equilibrium state. The proposed resilience framework is applied to the external-sector and the public-sector economies of several countries to illustrate its applicability. 相似文献
110.
A formal technique for incorporating two specification paradigms is presented,in which an algebraic specification is implemented by a set of abstract procedures specified in pre and post-condition style.The link between the two level specifications is provided via a translation from terms of algebraic specifications into temporal logic formulae representing abstract programs.In terms of translation,a criterion for an abstract implementation satisfying its specification is given,which allows one to check the consistency between the two levels of specifications.The abstract implementations can be refined into executable code by refining each abstract procedure in it.It is proved that the satisfication relation between a specification and its implementations is preserved by such refinement steps. 相似文献